Inside, while the 2015 BMW i8 is dubbed a 2+2 coupe, there's no legroom to speak of in the rear seats with adults up front. Each rear seat holds one good-sized backpack, and that's about it.

The dashboard and console will be recognizable to BMW drivers as a product of the Bavarian company. While the i8 shares the freestanding central screen of the BMW i3 electric car, there's a more conventional electronic instrument display cluster behind the steering wheel.

The graphics on the screen, manipulated by the iDrive controller on the console, are also just like those in the rest of the BMW family--with several additional layers of functions for the new powertrain.

The interior of the cars we drove was a very pleasant ivory and black two-tone, with blue accent lines that turned out to light up via LEDs inside when the car passed through tunnels or other dark areas.

The blue accents in general set the i8 apart from other sport coupes, coming in just under the bar for "too busy" (in our eyes) and differentiating it from fastback two-doors that share its overall shape.

One of our favorite features was the bright blue color of the seat belts, giving a pleasant twist to the normally invisible black belt webbing--and a definite luxury feel of "surprise and delight."

Perhaps the most surprising aspect of the design is the tapered rear bodywork. Long, narrow "wings" on the sides of the glass rear hatch all but cover a deep grooved tunnel on the tops of the rear fenders, further hidden by a little outboard kickup in each taillight.

It's subtle, but it's also startling once you look at it--no other car we know of has anything similar, and it's a quiet way of underscoring the BMW i8's difference from other coupes.

The challenge that poses, of course, is what to compare to the 2015 i8.

What competes with i8?

BMW executives uniformly describe their plug-in hybrid two-door as a "new category of sports coupe" with "high efficiency" and "environmentally responsible design," though we remain thoroughly unconvinced that such a segment actually exists--at least in the U.S. market.

Press them further, and they'll suggest the Audi R8 and Porsche 911 as the nearest competitors. Both are effectively two-seat performance coupes with prices above $100,000 for the bulk of the model range.

Is the Tesla Model S a competitor? Certainly BMW and Tesla owners likely share some psychographic similarities--just look at the number of BMWs of all models on the roads of Silicon Valley--but the Model S is a five-seat family sedan, and all-electric as well.

Pretty much everyone at the drive event quickly dismissed the Cadillac ELR as a competitor. It too is a striking plug-in coupe, but its performance isn't up to the level of the BMW's, and it remains a Cadillac at a time when that brand has not yet emerged as a straight-across competitor to German luxury brands.

The overall conclusion is that at its likely low volumes (5,000 globally during its first year), the 2015 BMW i8 is likely to sell purely on its looks and its status as BMW's current halo car.

It's an excellent first effort as a plug-in hybrid, and paired with the BMW i3 battery-electric hatchback--both designed on aluminum chassis structures holding the running gear, with carbon-fiber reinforced plastic body shells--it indicates just how serious BMW is about staking a claim in the fast-growing plug-in car field.

We suspect many buyers would prefer the i8 to have twice its likely range, taking it above 30 miles and making it possible to run a much higher percentage of its miles on grid power.

But that may ignore its purpose, which is to show that a sports coupe can use a combination of battery electric power and a combustion engine to run much more efficiently on average--and still look good and perform well.